Heritability of immunological characteristics in Florida Scrub-Jays (Aphelocoma coerulescens)

Abstract

The degree to which immunological phenotype is under genetic control as opposed to plasticity in response to variable environmental conditions remains largely unknown in natural populations. We assessed different aspects of immune function in father–son pairs in Florida Scrub-Jays (Aphelocoma coerulescens (Bosc, 1795)), a species with high natal philopatry, to determine if the responses were heritable. Specifically, we examined heritability of the (i) heterophil to lymphocyte ratio, (ii) ability to kill the Gram-negative bacteria Escherichia coli in an in vitro challenge, and (iii) ability to kill the Gram-positive bacteria Staphylococcus aureus in an in vitro challenge. The heritability (h2) of each of the three measures described above was estimated as twice the slope of the regression (2β) from the mean value for each measure for sons on the mean value of the same measure for the father. Heritability estimates were high for all measures: heterophil to lymphocyte ratios (h2 = 1.54 ± 0.31) and E. coli (h2 = 1.84 ± 0.12) and S. aureus (h2 = 1.13 ± 0.16) killing abilities. Our results show a strong correlation between father and son immune function, as well as the influential nature of genetic inheritance and potential environmental effects associated with high natal philopatry on physiology.